The standard water closet or toilet tank normally holds a volume of about 45 litres of water, most of the water being used with each flush of the toilet. With the present need to conserve water, and also to reduce the cost of water used, there is a need to reduce the volume of water used per flush. The need is particularly great in arid areas of the country and also in institutional types of buildings such as hospitals or hotels.
There have been many attempts at reducing the volume of water used per flush. Many people merely insert solid items such as a brick into the water closet so as to displace a portion of the available volume. While this will work there is always the possibility of chemicals leaching from the brick and contaminating the water or staining the interior of the water closet. Other people have placed plastic pails or tubs in the water closet so that they will fill with water but will not permit the contained water to leave, thereby reducing the volume flushed. These will work but they tend to move around within the water closet and they can interfere with the valve mechanism of the water closet. Other people have devised weirs which fit within the water closet and hold back a certain volume of water, preventing it from leaving with the rest of the flush water. The weirs are somewhat expensive to produce and require a degree of manual dexterity to properly position within the water closet. There is thus a need for a simple, inexpensive device that will reduce the flush volume, is easy to install, and will have no deleterious effect on the water or the water closet itself.